1. Field of the Invention
This invention relates, in general, to hydraulic couplings, and specifically to hydraulic couplings used in undersea drilling and production applications. More particularly, the invention involves an undersea hydraulic coupling having an improved radial seal with a dovetail interfit for holding and positioning the seal in place upon separation of the male member from the female member of the coupling.
2. Description of the Related Art
Subsea hydraulic couplings are old in the art. The couplings generally consist of a male member and a female member with seals to seal the junction between the male and female members. The female member generally has a cylindrical body with a relatively large diameter bore at one end and a relatively small diameter bore at the other. The small bore facilitates connections to hydraulic lines, while the large bore contains the seals and receives the male portion of the coupling. The male member includes a probe section insertable into the large bore of the female member. According to various embodiments of the device, the seals either abut the end, or face, of the male member or engage the male member about its outer circumference. Hydraulic fluid is then free to flow through the female and male portions of the coupling and seals prevent that flow from escaping about the joints of the coupling.
A check valve may be installed in the female member and also in the male member. Each check valve is open when the coupling is made up; however, each check valve closes when the coupling is broken so as to prevent fluid from leaking out of the system of which the coupling is part.
In U.S. Pat. Nos. 4,694,859 and 5,762,106 to Robert E. Smith III, an undersea hydraulic coupling and metal seal is disclosed. A reusable metal seal engages the circumference of the probe when it is positioned within the female member body. The seal is held in place by a cylindrical body or retainer. When the male and female portions of the coupling are parted under pressure, the retainer prevents the metal seal from blowing out through the bore of the female member.
U.S. Pat. No. 4,900,071 to Robert E. Smith III discloses an undersea hydraulic coupling with a dovetail seal. A two-piece retainer restrains radial movement of a wedge-shaped annular seal into the central bore of the female member. The seal is restrained from radial movement by a dovetail interfit with a circumferential shoulder on at least one of the retainer sleeve and the retainer locking member. U.S. Pat. Nos. 5,052,439, 5,099,882, 5,203,374, 5,232,021 to Robert E. Smith III also show undersea hydraulic couplings with dovetail seals. The inner cylindrical surface of the annular seal engages the circumference of the male member or probe as the probe is inserted through the retainer into the female member. As the male member or probe is pulled out of the female member bore, the leading face of the male member reaches the soft annular seal intermediate that bore. When the face reaches the midpoint of the soft annular seal, the dovetail interfit prevents the seal being imploded into the bore, as the seawater and/or hydraulic fluid enter the bore at high pressure.
It is desirable to enhance the sealing effect of the dovetail seals of the foregoing type, especially at greater depths in subsea drilling and production applications. In the past, many hydraulic couplings included two or more seals to assure that hydraulic fluid would not leak from the coupling at higher pressures and greater subseas depths. While seals having a dovetail interfit prevent blowing out or implosion of the seal into the bore of the female member, the seal alone is insufficient in certain applications. It is desirable to enhance the seal especially in higher pressure hydraulic systems and at greater depths. For example, a second pressure-energized seal may be used to seal radially between the male and female members, to supplement the first dovetail seal. However, the use of two or more seals and the structural design of the hydraulic coupling for such seals increases in complexity and cost when two or more seals are employed. Accordingly, a coupling having a seal that is able to provide functional capabilities of a dovetail-shaped seal and a pressure-energized seal is needed.